Routing

This entry contains definitions for routing with routing
tables/longest prefix matching. A routing table entry is modelled as
a record of a prefix match, a metric, an output port, and an optional
next hop. A routing table is a list of entries, sorted by prefix
length and metric. Additionally, a parser and serializer for the
output of the ip-route command, a function to create a relation from
output port to corresponding destination IP space, and a model of a
Linux-style router are included.